The present invention relates to an electrophotographic image forming apparatus and a process cartridge removably installable in the main assembly of an electrophotographic image forming apparatus.
Here, the term xe2x80x9celectrophotographic image forming apparatusxe2x80x9d refers to an apparatus that forms an image on recording medium with the use of an electrophotographic image forming method. As an example of an electrophotographic image forming apparatus, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, and the like), a facsimile apparatus, a word processor, and the like can be included.
A process cartridge is: a cartridge, in which a charging means, either a developing means or a cleaning means, and an electrophotographic photosensitive member, are integrally placed, and which is removably installable in the main assembly of an image forming apparatus; a cartridge in which at least one of the processing means among a charging means, a developing means, and a cleaning means, and an electrophotographic photosensitive drum, are integrally placed, and which is removably installable in the main assembly of an image forming apparatus; or a cartridge in which at least a developing means among the aforementioned processing means, and an electrophotographic photosensitive member, are integrally placed, and which is removably installable in the main assembly of an image forming apparatus.
Conventionally, an electrophotographic image forming apparatus which employs an electrophotographic image forming process employs a process cartridge system, according to which an electrophotographic photosensitive member, and a single or a plurality of the aforementioned processing means, are integrally placed in a cartridge removably installable in the main assembly of an image forming apparatus. According to this process-cartridge system, an image forming apparatus can be maintained by the users themselves, without relying on service personnel, remarkably improving operational efficiency. Thus, a process-cartridge system is widely used in the field of an image forming apparatus.
In a process cartridge such as the one described above, a photosensitive drum is driven by the main assembly of an image forming apparatus, and the force for rotationally driving a development sleeve is transmitted to the development sleeve from the photosensitive drum. The force for rotationally driving a stirring member is transmitted also from the photosensitive drum through a gear train.
In recent years, an image forming apparatus that employs an electrophotographic image forming process has been developed to produce a high quality image without sacrificing its operational efficiency.
The present invention is a result of further development of the aforementioned conventional technologies.
The primary object of the present invention is to provide a process cartridge, the electrophotographic photosensitive drum of which is superior in rotational accuracy to a conventional one, and an electrophotographic image forming apparatus in which such a process cartridge is removably installable.
Another object of the present invention is to provide a process cartridge which can be more accurately positioned relative to the main assembly of an image forming apparatus than a conventional process cartridge, when the process cartridge is installed into the image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge is removably installable.
Another object of the present invention is to provide a process cartridge, the electrophotographic photosensitive drum and cartridge frame of which are positioned, independently from each other, relative to the main assembly of an image forming apparatus when the process cartridge is installed into the image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge can be removably installable.
Another object of the present invention is to provide a process cartridge in which the rotational load is smaller than in a conventional process cartridge, when the electrophotographic photosensitive drum rotates as the force for driving the electrophotographic photosensitive drum is transmitted from the main assembly of an image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge can be removably installable.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.